Method of loading tendons into the knee

ABSTRACT

A surgical method for loading ligament grafts into a joint. A longitudinal socket formed in a bone is intersected by a transverse pin. A flexible strand is drawn with the pin through the bone. A looped portion of the strand is diverted so as to protrude out of the entrance to the longitudinal socket. The ends of the strand remaining accessible on either side of the bone. The ligament graft is captured within the strand loop protruding from the entrance to the socket. The strand is retracted into the socket, drawing the graft into the socket by pulling on the accessible ends of the flexible strand. The graft is fixed in the socket using a transverse implant.

[0001] This application claims the benefit of U.S. ProvisionalApplication Serial No. 60/037,610, filed Feb. 12, 1997.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to reconstruction of the anteriorcruciate ligament (ACL), and, more specifically, to surgical graftfixation using semitendinosus and gracilis tendon autografts.

[0004] 2. Description of the Related Art

[0005] When a ligament or tendon becomes detached from associated bone,surgery usually is required to re-secure the ligament or tendon. Often,a substitute ligament, or graft, is attached to the bone to facilitatere-growth and permanent attachment. Various methods of ligament graftattachment are known, including staples, suture over buttons, andinterference screw fixation.

[0006] Various problems exist with the known fixation methods. Staplesand suture buttons are disadvantageous because they often do not providefixation sufficient to withstand the normal tensile loads. With suturebutton fixation, for example, a strand of suture couples the button andthe substitute ligament. This strand becomes the “weakest link in thechain,” and if the strand breaks, the ligament detaches.

[0007] A stronger graft attachment can be obtained by interference screwfixation, whereby an interference screw is used to wedge a graft boneblock to the wall of a graft tunnel. See, e.g., U.S. Pat. Nos.5,211,647, and 5,603,716, incorporated herein by reference.

[0008] Although interference screw attachment is more secure than usingstaples or suture buttons, it is sometimes neither possible nordesirable to provide such fixation, particularly in the femoral tunnel.In revision situations, for example, where a previous reconstruction hasbeen performed, placing a second femoral tunnel placed close to theprevious tunnel may not be indicated.

[0009] In other cases, a semitendinosus graft must be used because theprevious reconstruction used the mid third patellar tendon. Although abone-semitendinosus graft-bone construct may be prepared using aworkstation as disclosed in U.S. Pat. No. 5,397,357, such a procedure istime consuming, and may be undesirable for other reasons.

[0010] A fixation technique which provides strong attachment of asemitendinosus graft in the femoral tunnel, using a transverse implant,is disclosed in U.S. Pat. No. 5,601,562, of common assignment with thepresent application, and incorporated herein by reference. Thetransverse implant is inserted through a loop in a tendon graft. Athreaded portion of the implant screws into the bone as the implant isadvanced with rotation into the repair site. The technique isdisadvantageous, however, because the graft can become wrapped aroundthe implant as it is rotated. An improved bone implant is the subject ofa co-pending U.S. patent application, attorney docket no. P/1493-155.

[0011] In addition, the prior art technique noted above requires aforked insertion tool, and a large femoral tunnel is needed toaccommodate the forked insertion tool. As a result, the large femoraltunnel undesirably allows the graft to slide laterally, or “wipe”, backand forth, along the fixation implant. Moreover, the diameter of theimplant necessarily is limited by the size of the opening in the forkedinsertion tool.

[0012] As a further disadvantage, the technique also requires the extrasteps of forming and wedging a bone plug into the femoral tunnel afterinsertion of the ligament. Moreover, the technique does not accommodatea closed-loop graft construct, since the graft must have a free end inorder to be inserted with the forked insertion tool. Further, thetechnique may not be indicated in revision procedures.

[0013] Various endoscopic techniques and instruments relating to graftfixation are known in the prior art and can be used in the practice ofthe present invention. U.S. Pat. No. 5,320,636 to Schmieding discussesan endoscopic drill guide for graft tunnel location. U.S. Pat. No. Des.378,780 illustrates a cannulated headed reamer as can be used in femoralsocket formation. U.S. Pat. Nos. 5,269,786 and 5,350,383 disclose drillguides for location of bone tunnels.

[0014] The need exists for fixation techniques that utilize narrowerfemoral/tibial tunnels, to prevent wiping, and that do not require theinsertion of bone plugs. Also, the need exists for graft ligamentloading techniques that can accommodate closed-looped grafts, that donot require specialized insertion tools to load the graft into the knee,and that can be indicated in certain revision procedures.

SUMMARY OF THE INVENTION

[0015] The present invention overcomes the problems of the prior art andfulfills needs such as those noted above by providing a surgical methodfor loading tendon grafts into a joint and fixating the grafts using atransverse, intraosseous implant. The inventive technique advantageouslyuses narrow tibial and femoral tunnels, and eliminates the use ofsutures, tapes, or extra-osseous metal fixation devices. The procedurealso is indicated for revisions that would otherwise be jeopardized bysecondary femoral tunnel creation. In addition, the technique can beimplemented using a transverse implant that is advanced by impactioninto the bone.

[0016] As applied in the knee, the method includes the use of standardtechniques to drill a longitudinal tunnel in the tibia. Subsequently, afemoral socket is formed, preferably in the lateral femoral condyle.According to the present invention, forming the socket is preferred toforming a tunnel through the lateral femoral cortex. Advantageously, thediameters of the tibial tunnel and femoral socket are made just largeenough to accommodate the graft in a snug fit.

[0017] A tunnel hook, mounted on a cross-pin drill guide, is insertedthrough the tibial tunnel and into the femoral socket. A drill pindirected by the drill guide is drilled through the femur to intersectthe femoral socket. The drill pin passes through the capture slot of thetunnel hook.

[0018] A hole then is formed in the femur, preferably using a cannulateddrill placed over the guide pin, to accommodate a threaded section ofthe transtibial implant. A channel is formed in the lateral femoralcortex to accommodate the remainder of the implant, preferably using adilator placed over the guide pin.

[0019] Next, a flexible strand, preferably a wire formed of nitinol, isattached to the guide pin and pulled through the femur. Equal lengths ofthe strand protrude from the medial and lateral sides of the femoralshaft, and are secured to prevent accidental pull-out. The tunnel hookis withdrawn, the strand being captured in the slot of the hook.

[0020] The hook is retracted completely, through the femoral socket andout of the tibial tunnel, such that a loop of the flexible strandprotrudes from the entrance to the tunnel. Free ends of the strandremain exposed on either side of the femoral shaft.

[0021] The graft is passed through the diverted loop of the flexiblestrand. The loop is retracted into the femoral socket by pulling evenlyon the medial and lateral ends of the strand. As a result, the graft isdrawn into the socket.

[0022] The cannulated implant is placed over the wire and driven intothe femur. The implant preferably is formed with back-biting threads.Accordingly, the implant easily can be impact driven into the repairsite, and yet can be removed if necessary by rotation. The cannulatedimplant passes over the strand and under the tendon, thus securing thegraft in the femoral socket.

[0023] Tibial fixation of the graft can be performed by various knownmethods, including interference screw fixation, which provides the mostsecure post-operative result; distal fixation with a cancellous screwusing a post and washer technique; and a belt buckle staple techniqueutilizing a pair of ligament staples.

[0024] An alternative method of tendon loading is also provided for aclosed-loop graft reconstruction. According to the alternative method, aflexible line is joined to one end of the strand. A strand/line loop isformed so as to protrude from the entrance to the tibial tunnel andpresent the junction between the strand and the line. The strand and theline are dejoined, opening the strand/line loop to accept the graft. Thestrand and line are rejoined so as to capture the graft, and theprocedure continues substantially as set forth above.

[0025] Other features and advantages of the present invention willbecome apparent from the following description of the invention whichrefers to the accompanying drawings. For example, although thedescription herein relates to ACL grafts and forming femoral tunnels inthe knee, it will become apparent that expanded indications for theinventive method include other joints and replacement of other ligamentor tendon structures using various types of graft constructs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is an elevation of a tunnel hook according to the presentinvention.

[0027]FIG. 2 is a distal end view of the tunnel hook of FIG. 1.

[0028]FIG. 3 is an elevation of a drill pin according to the presentinvention.

[0029]FIG. 4 is an enlarged view of the distal tip of the drill pin ofFIG. 3.

[0030]FIG. 5 is a distal end view of the drill pin of FIGS. 3 and 4.

[0031]FIG. 6 is an elevation of a tunnel dilator according to thepresent invention.

[0032]FIG. 7 illustrates a graft-passing wire according to the presentinvention.

[0033]FIG. 8 illustrates a transverse implant having back-biting threadsaccording to the present invention.

[0034]FIG. 9 is an enlarged detail view of the back-biting threads ofthe transverse implant illustrated in FIG. 8.

[0035]FIG. 10 is a schematic view of a hook and a drill pin mounted on adrill guide and disposed within the femoral socket according to thepresent invention.

[0036]FIG. 11 is a schematic view of a tunnel dilator being used to forma femoral channel for the transverse implant according to the presentinvention.

[0037]FIG. 12 illustrates a flexible strand attached to the drill pinand being pulled through the femur according to the present invention.

[0038]FIG. 13 illustrates a loop of the flexible strand being pulled bythe hook and out through the femoral socket according to the presentinvention.

[0039]FIG. 14 illustrates the flexible strand loop having been divertedthrough the tibial tunnel, capturing a ligament graft, and pulling thegraft into the tibial tunnel according to the present invention.

[0040]FIG. 15 illustrates the ligament graft, having been loaded throughthe longitudinal tibial tunnel and into the femoral socket, beingfixated using a transverse implant according to the present invention.

[0041]FIG. 16 illustrates a completed tendon graft repair includingtibial fixation with an interference screw.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Referring initially to FIGS. 1 and 2, the present inventioninvolves the use of a slim, longitudinal tunnel hook 2, which includes ashaft having a distal end and a proximal end. The distal end of tunnelhook 2 is provided with a hook 4, having a capture slot 6.

[0043] Various features of tunnel hook 2 are provided for ease of use inthe inventive procedure of the present invention. The purpose of thefollowing features will become more clear in light of the methoddescribed below. Angled opening 8 allows escape of a graft-passing wirefrom capture slot 6. Channels 10 on either side of hook 4 accommodateportions of the graft-passing wire as it forms a loop through a femoraltunnel. The proximal end of tunnel hook 2 features a mounting flange 11for engagement with a drill guide.

[0044] Referring to FIGS. 3, 4, and 5, the invention also involves theuse of a drill pin 12, which includes an elongated, narrow shaft havinga pointed distal end and a proximal end. The distal end of drill pin 12is provided with a sharp, trocar tip 14 and a fluted drilling region 16disposed adjacent to and proximal the faces of trocar tip 14. Theproximal end of drill pin 12 includes a hook 18 having an angled openinginto its capture slot for engaging the graft-passing wire, as describedmore fully below.

[0045] Referring to FIG. 6, a tunnel dilator 20 is shown. Tunnel dilator20 has a tapered distal end and a proximal end. Dilator 20 is cannulatedto be received over drill pin 12. The dilator has an initial taper 22 atthe distal end for insertion into the bone where the drill pin enters. Acylindrical portion 24 forms a channel in the femur for receiving animplant shaft. An interim fluted portion 26 can be providedalternatively to form a hole for receiving threads of the implant, asdescribed below. A depth stop 28 is formed proximally.

[0046] Referring to FIG. 7, a nitinol graft-passing wire 30 is shown.Passing wire 30 includes a flexible portion 32 having a loop 34 formedon the distal end and a rounded proximal end 36.

[0047]FIGS. 8 and 9 illustrate a transverse implant 40. Implant 40 has athreaded proximal end and a threaded distal ends. The implant iscannulated to be received over graft-passing wire 30. The implant has ataper 42 formed toward the distal end. The proximal end includesback-biting, helical threads 44 and a drive socket 46. As shown indetail in FIG. 9, threads 44 have a sloping distal face 48 and aproximal face 50 meeting at a radiused edge 52. Distal face 48 forms anangle A of about 72 with a perpendicular to the central axis of theimplant. Proximal face 50 forms an angle B of about 18 with theperpendicular. The implant can be driven by impaction into bone, andthen, if necessary, can be subsequently removed by screw rotation asdiscussed below.

[0048] The method of the present invention is described with referenceto FIGS. 10 through 16. A longitudinal tibial tunnel 56 is formed usingknown techniques of drilling up through the tibia 58. Reproducibletunnel placement is achieved using instruments that referenceintra-articular anatomical constants. A cannulated drill, received overa guide, is used to drill the tibial tunnel. Depending on the size ofthe graft, tunnel diameters of 7, 8, 9, and 10 mm are can be used.

[0049] Once the tibial tunnel is formed, a cannulated headed reamer isused to form a closed-ended socket 60 in the femur 62. The socket isformed to a minimum depth of about 40 mm to accommodate the insertiondepth of tunnel hook 2. The knee should be placed in 90 of flexion whenforming the tibial tunnel and femoral socket.

[0050] The tunnel and socket can be modified in various ways usingtunnel taps. For example, crenulations formed in the tibial tunnelprovide additional friction and helps eliminate unwanted graft rotationduring interference screw insertion. A spiral groove formed in thetunnel wall provides additional interference friction of the graftcollagen against the compressed cancellous bone in the tunnel. A raspmay be used to create an oval-shaped tunnel and femoral socket toaccommodate insertion of four tendon strands.

[0051] After the tibial tunnel and femoral socket are complete, tunnelhook 2, fitted onto a C-ring cross-pin drill guide 64, is insertedthrough tibial tunnel 56 and into femoral socket 60. Tunnel hook 2 willcapture within slot 6 the graft-passing wire 12 used in loading thegraft tendons into the femoral socket, as described below with respectto FIGS. 12 and 13.

[0052] Referring again to FIG. 10, with tunnel hook 2 and drill guide 64in place, a 2 mm drill pin sleeve 66 is advanced in the direction ofarrow A up to the skin proximal to the femoral condyle to indicate anincision site. The drill guide is positioned to allow the pin to passparallel to the coronal plane, without excessive posterior or anteriordivergence. A 2-cm incision is made transversely at this site throughthe skin and fascia lata, and soft tissue is cleared down to thecondyle. Drill pin sleeve 66 is advanced until it contacts bone.Over-tightening of the drill pin sleeve against the femoral cortex isavoided to prevent the drill pin from deviating and missing capture slot6 of tunnel hook 2. A depth indicator on the sleeve is used to gauge thelength of implant 40 that will be required.

[0053] With the sleeve in position against the cortical bone, drill pin12, 2 mm. in diameter, is chucked into a power drill 68, and advancedwith rotation through the femur until it exits the skin on the medialside 70. To ensure that the drill pin passes within the capture slot 6of tunnel hook 2, torque on the drill guide and changes in knee flexionare avoided during drilling.

[0054] Referring to FIG. 11, a cannulated drill is placed over the guidepin to drill a hole 71 to accommodate threaded section 44 of implant 40.The drill is replaced with tunnel dilator 20, which is used to form achannel in the femur for the remainder of implant 40. Tunnel dilator 20is mounted onto a driver/extractor 72 and driven with a mallet in thedirection of arrow B up to the depth stop 28.

[0055] Referring to FIG. 12, once the channel has been formed, loop 34of nitinol graft-passing wire 30 is hooked onto hook 18 on the proximalend of drill pin 12. By pulling on the drill pin, the graft-passing wireis drawn through the femur until it is positioned with equal lengths ateither end protruding from the medial and lateral sides of the femoralshaft. Hemostats 74 are clipped onto the ends of the wire to preventthem from being pulled into the transverse femoral tunnel 70, as shownin FIG. 14.

[0056] Referring to FIGS. 13 and 14, once the graft-passing wire hasbeen drawn through the femur, tunnel hook 2 is retracted from femoralsocket 60 and tibial tunnel 56, pulling graft-passing wire 30 with it toform a loop that protrudes from the entrance of tibial tunnel 56 on theanterior tibial cortex. The semitendinosus and gracilis tendons 76 areplaced evenly over the wire loop, and the loop containing the tendons isretracted in the direction of arrow C back through the tibial tunnel andinto the femoral socket by pulling evenly on the medial and lateral endsof the graft-passing wire, as shown by arrows D and E, respectively.Twisting of the graft during insertion is avoided.

[0057] Referring to FIG. 15, once the tendons 76 have been drawncompletely into femoral socket 60, implant 40 is inserted over the guidewire and advanced by hand until the threaded section 44 contacts thefemur. An implant impactor 78 is chucked into driver/extractor 72 andplaced over the wire 30. The head of the implant 40 is engaged and amallet is used to drive the implant into the femur until a depth stop 82on the driver 78 contacts the cortical bone. Pulling on the tendons 76is avoided during impaction of the implant 40.

[0058] The implant is advanced along the wire in the direction of arrowF. The implant passes under the loop formed in tendons 76, toward themedial side of the femur, to provide cross-pin support of tendons 76. Ifremoval of the implant should become necessary, reverse cutting threads44 facilitate removal by unscrewing the implant with a 3.5 mm hex headscrewdriver.

[0059] Referring to FIG. 16, the repair is completed by interferencescrew 84 fixation of graft 76 in tibial tunnel 56. The femoral tunnel isnarrow so that tendons 76 fit snugly within tibial tunnel 56 and femoralsocket 60, thus avoiding wiping of the tendons along the implant.

[0060] Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art.Therefore, the present invention is to be limited not by the specificdisclosure herein, but only by the appended claims.

What is claimed is:
 1. A method of surgery, comprising: forming a holein a bone, the hole having an entrance; intersecting the hole with aflexible strand positioned transverse to the hole; diverting a portionof the strand out through the hole entrance; engaging a graft with thediverted portion of the strand; and pulling a portion of the graft withthe strand into the hole.
 2. The method of claim 1, further comprisingthe step of securing the graft in the hole using a transverse implant.3. The method of claim 2, wherein the implant is cannulated, the methodfurther comprising the step of guiding the implant using the strand. 4.The method of claim 1, wherein the step of forming a hole comprisesforming a socket that is closed at one end.
 5. The method of claim 1,wherein the step of diverting the strand comprises forming a loop in thestrand outside the entrance to the hole.
 6. The method of claim 1,wherein the step of diverting the strand into the transverse tunnelcomprises engaging the strand with a hook.
 7. The method of claim 6,further comprising the step of inserting the hook into the hole.
 8. Themethod of claim 7, wherein the hook is inserted into the prior tointersecting the hole with the strand.
 9. The method of claim 5, furthercomprising the steps of: opening a junction in the strand loop outsidethe entrance to the hole to form two free ends; reforming the loop byreattaching the two free ends so as to capture a graft within thereformed loop.
 10. A surgical method, comprising the steps of: forming ahole in bone, the hole having an entrance; inserting a hook having aneye into the hole; drilling a guide pin through the bone so as tointersect the socket, the guide pin passing through the eye of the hook;drawing a wire through the bone using the guide pin; diverting a loop inthe wire out through the entrance to the hole using the hook; capturinga tendon graft with the loop in the wire; retracting the wire so as todraw the graft into the hole; and securing the graft within the hole.11. The method of claim 10, wherein the step of securing the graftcomprises engaging the graft using a transverse implant.
 12. The methodof claim 10, wherein the step of securing the graft comprises advancingthe implant through a loop in the graft.